A valve assembly for a fluid injection valve typically comprises a valve body comprising a cavity with a fluid inlet portion and a fluid outlet portion and a valve needle axially moveable in the cavity. The valve needle prevents a fluid flow through the fluid outlet portion in a closed position and releases the fluid flow through the fluid outlet portion in further positions. The valve needle may be actuated by an electromagnetic actuation unit.
DE 103 12 319 A1 discloses an injection valve with a lower magnetic ring to improve the performance of an electromagnetic valve. In this type of injection valve, the housing is often machined to create a pocket for the coil and to fit an inlet tube and a valve body. The material used for the housing has an impact on the magnetic performance of the injection valve, especially in conditions where it operates with a high fuel pressure. However, the choice of material used for the housing also has a severe influence on the costs of the injection valve. Furthermore, the existence of air gaps between parts which are penetrated by the magnetic flux also influences the magnetic performance.